Welcome in H.C.M.
By your symptoms I came to knew that you are having tingling behind your left ear and your left half of your head.
Anatomically area of our skull behind the ear has got sensory nerve
supply from cervical spinal nerve. Therefore your symptoms are due to Radiculopathy
of cervical nerves
may be secondary to cervical spondylosis
To confirm it and to manage it you should do-
1- M.R.I. of neck.
2- Blood sugar ( F & PP).
By these investigations and clinical examination one may made diagnosis and that may be accordingly managed.
I hope above answers your query.